From 7737daab8bc713dad04181878ee6d8e0ac9d935c Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Sat, 24 May 2025 13:34:36 +0300 Subject: [PATCH v6 3/3] Remove redundant ReplicationSlotsComputeRequiredLSN calls The function ReplicationSlotsComputeRequiredLSN is used to calculate the oldest slots' required LSN. It is called every time when restart_lsn value of any slot is changed (for example, when a slot is advancing). The slot's oldest required LSN is used to remote old WAL segments in two places - when checkpoint or restart point is created (CreateCheckPoint, CreateRestartPoint functions). Old WAL segments seems to be truncated in these two functions only. The idea of the patch is to call ReplicationSlotsComputeRequiredLSN in CreateCheckPoint or CreateRestartPoint functions only, before call of RemoveOldXlogFiles function where old WAL segments are removed. There is no obvious need to recalculate oldest required LSN every time when a slot's restart_lsn is changed. The value of the oldest required lsn can affect on slot invalidation. The function InvalidateObsoleteReplicationSlots with non zero second parameter (oldestSegno) is called in CreateCheckPoint, CreateRestartPoint functions only where slot invalidation occurs with reason RS_INVAL_WAL_REMOVED. Once we update the oldest slots' required lsn in the beginning of these functions, the proposed patch should not break the behaviour of slot invalidation function in this case. --- src/backend/access/transam/xlog.c | 4 ++++ src/backend/replication/logical/logical.c | 1 - src/backend/replication/logical/slotsync.c | 4 ---- src/backend/replication/slot.c | 5 ----- src/backend/replication/slotfuncs.c | 2 -- src/backend/replication/walsender.c | 1 - 6 files changed, 4 insertions(+), 13 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 0a7f7a71d8b..bdfd0a59ab7 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7324,6 +7324,7 @@ CreateCheckPoint(int flags) * might be advanced concurrently, so we call this before * CheckPointReplicationSlots() synchronizes replication slots. */ + ReplicationSlotsComputeRequiredLSN(); slotsMinReqLSN = XLogGetReplicationSlotMinimumLSN(); /* @@ -7528,6 +7529,7 @@ CreateCheckPoint(int flags) * cleanup. Then, we must synchronize the replication slots again in * order to make this LSN safe to use. */ + ReplicationSlotsComputeRequiredLSN(); slotsMinReqLSN = XLogGetReplicationSlotMinimumLSN(); CheckPointReplicationSlots(shutdown); @@ -7901,6 +7903,7 @@ CreateRestartPoint(int flags) * might be advanced concurrently, so we call this before * CheckPointReplicationSlots() synchronizes replication slots. */ + ReplicationSlotsComputeRequiredLSN(); slotsMinReqLSN = XLogGetReplicationSlotMinimumLSN(); if (log_checkpoints) @@ -8001,6 +8004,7 @@ CreateRestartPoint(int flags) * cleanup. Then, we must synchronize the replication slots again in * order to make this LSN safe to use. */ + ReplicationSlotsComputeRequiredLSN(); slotsMinReqLSN = XLogGetReplicationSlotMinimumLSN(); CheckPointReplicationSlots(flags & CHECKPOINT_IS_SHUTDOWN); diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c index 081e6593722..34e973393c2 100644 --- a/src/backend/replication/logical/logical.c +++ b/src/backend/replication/logical/logical.c @@ -1925,7 +1925,6 @@ LogicalConfirmReceivedLocation(XLogRecPtr lsn) SpinLockRelease(&MyReplicationSlot->mutex); ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); } } else diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c index 656e66e0ae0..30662c09275 100644 --- a/src/backend/replication/logical/slotsync.c +++ b/src/backend/replication/logical/slotsync.c @@ -335,7 +335,6 @@ update_local_synced_slot(RemoteSlot *remote_slot, Oid remote_dbid, SpinLockRelease(&slot->mutex); ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); } return updated_config || updated_xmin_or_lsn; @@ -502,9 +501,6 @@ reserve_wal_for_local_slot(XLogRecPtr restart_lsn) slot->data.restart_lsn = restart_lsn; SpinLockRelease(&slot->mutex); - /* Prevent WAL removal as fast as possible */ - ReplicationSlotsComputeRequiredLSN(); - XLByteToSeg(slot->data.restart_lsn, segno, wal_segment_size); /* diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index 600b87fa9cb..dd18fe10f7d 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -1008,7 +1008,6 @@ ReplicationSlotDropPtr(ReplicationSlot *slot) * limits. */ ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); /* * If removing the directory fails, the worst thing that will happen is @@ -1494,9 +1493,6 @@ ReplicationSlotReserveWal(void) slot->data.restart_lsn = restart_lsn; SpinLockRelease(&slot->mutex); - /* prevent WAL removal as fast as possible */ - ReplicationSlotsComputeRequiredLSN(); - /* * If all required WAL is still there, great, otherwise retry. The * slot should prevent further removal of WAL, unless there's a @@ -2014,7 +2010,6 @@ restart: if (invalidated) { ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); } return invalidated; diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c index 36cc2ed4e44..3300fb9b1c9 100644 --- a/src/backend/replication/slotfuncs.c +++ b/src/backend/replication/slotfuncs.c @@ -583,7 +583,6 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS) * advancing potentially done. */ ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); ReplicationSlotRelease(); @@ -819,7 +818,6 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot) ReplicationSlotMarkDirty(); ReplicationSlotsComputeRequiredXmin(false); - ReplicationSlotsComputeRequiredLSN(); ReplicationSlotSave(); #ifdef USE_ASSERT_CHECKING diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index d751d34295d..dff749f00a8 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -2384,7 +2384,6 @@ PhysicalConfirmReceivedLocation(XLogRecPtr lsn) if (changed) { ReplicationSlotMarkDirty(); - ReplicationSlotsComputeRequiredLSN(); PhysicalWakeupLogicalWalSnd(); } -- 2.39.5 (Apple Git-154)